This invention relates to a process and apparatus for cleaning air passing to the inlet of a gas turbine, and more particularly, this invention relates to a process and apparatus for reducing contaminants present in air passing to the inlet of a gas turbine.
The operation of a gas turbine is well known. In the initial phase of a gas turbine's cycle, an air compressor stage consumes approximately 60 percent of the work done by the power turbine. As such, the efficiency of the compression stage has a large affect on the efficiency of the whole cycle. To maintain peak efficiency, the compressor would have to be kept extremely clean and the blades would have to maintain their original design profile and surface smoothness. However, with these compressors pulling in ambient air laden with particulate material and in some environments cannot be maintained. The compressor blades are eroded by the larger particles. Smaller particles stick to the blades changing the shape and smoothness of the blades. This is called "fouling." Both the small particles and corrosive volatiles work to corrode the blade surface. Gas turbines, therefore, require "clean" air to prevent fouling, corrosion, and erosion of the gas turbine internal components such as the compressor blades.
The "state-of-the-art" method for cleaning inlet air to gas turbines is to use a combination of filters for removing particulate in the air. However, air filters, alone, have not been successful in eliminating the fouling, erosion, and corrosion damage to the compressor. The result is loss of efficiency and damage to expensive compressor blading. The air contaminants in either particulate or gaseous form penetrate even the best filter system on the market, and enter the a compressor section of a gas turbine engine. The particulates which make their way to the compressor will erode the compressor blades, or stick to the blades which cause fouling and often corrosion and pitting. The corrosion can weaken a blade to the failure point or, as a minimum, degrade airfoil performance. In addition, both solid and gaseous contaminants which make it through the compressor will enter the turbine section, causing a buildup of material which degrades the machine performance and causes hot corrosion of the hot end parts. The costs to a gas turbine operator from degraded performance and worn and/or corroded parts replacement due to contaminated inlet air can exceed a million dollars per year per turbine.
It is, therefore, desirous to install an apparatus for cleaning the inlet air directly down stream or particulate filters used in conjunction with gas turbines. More particularly, it is desired to provide an air scrubber which removes gaseous and solid contaminants from air passing to a gas turbine which can cause corrosion of turbine parts. It is further desired to provide an apparatus for scrubbing air and which reduces buildup of solid materials in the turbine.
It is further desired to provide an air cleaning apparatus which has an intense air scrubbing action not present in any evaporative coolers in gas turbine inlet systems. In addition, it is desired to provide an air cleaning apparatus which will remove particles and gaseous contaminants which get through the dry filter systems on the market today. It is further desired to provide an air cleaning system which will have a relatively low operating cost.